


Indivisible

by dracoqueen22



Series: Interwoven [1]
Category: Transformers (Bay Movies)
Genre: Background Character Death, Brother Feels, Brotherly Angst, Canon Typical Violence, Canonical Character Death, Canonical Character Resurrection, M/M, Plug and Play Sex, Tactile Interfacing, Twin themes
Language: English
Status: Completed
Published: 2013-10-04
Updated: 2014-05-16
Packaged: 2017-12-28 08:40:12
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 7
Words: 8,824
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/989996
Author URL: https://archiveofourown.org/users/dracoqueen22/pseuds/dracoqueen22
Summary: <blockquote class="userstuff">
              <p>Love does not preclude hate, nor does it presume loyalty. Nothing proves this more than the thin line drawn across Cybertron, between brother and brother, twin and twin, Autobot versus Decepticon.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> This was originally posted in my fic collection "Database in Transmission" until the little ficlets grew a story of their own. I've collected them here for reader's convenience.

Once upon a time, Sideswipe had been a twin. He had shared his spark and functioning with another mech. He was never alone.

He loved his twin inasmuch as he understood love. Though sometimes he hated his other half, too.

Love, Sideswipe discovered, did not preclude hate.

Once upon a time, Optimus Prime had a brother, a twin in everything but station. A mech with half his spark with whom he shared rulership and all else that mattered.

Love, Optimus had also learned, did not presume loyalty.

There they were, two abandoned mechs on the edge of a rusty battlefield, staring across hordes of fallen frames, littered over an energon-soaked expanse. Ash and spent ions clung in a dense cloud to the sparse atmosphere.

Sideswipe had energon on taloned hands, dripping down his chestplate, coating the streaks of gold glaringly obvious on the once-glittering silver of his paint.

Optimus' hands were clean, at least of visible stains. His optics tracked the retreating backplate of a warmonger. His frame remembered the fierce beating he had absorbed until a retreat was called or victory assumed.

No one, in truth, had won here.

Again, Optimus realized. Time and again he would face the consequences of his own weakness. He would suffer for the spark he could not bear to take.

Cybertron would suffer. Her people would suffer.

Because until now Optimus had not understood the cost of love. He hadn't understood how it could cut so deep, pollute from the inside out, and disturb the natural state.

Sideswipe did.

Optimus turned his gaze on the silver warrior, energon dripping the last spare drops from his hands, limp at his sides.

Sideswipe had the courage to do what he must. He had looked into the optics of his other half and hadn't faltered. He had not let his weakness rule him.

Optimus must learn from his example. He would not be able to win this war if he could not. Cybertron must be protected, and her people, too.

The unbreakable bonds must be shattered, no matter the cost.

The scientist within him was of no use here and must be cast aside. Optimus Prime as he knew himself would be abandoned as well. He must become the warrior Cybertron needed. And he must prepare himself for the next confrontation.

The outcome must not be allowed to repeat itself.

"Never again," Optimus said, his soft proclamation too loud in the after-battle silence.

Sideswipe looked up at him as Optimus lay a hand on his shoulder, over a deep gash in thick armor, metal scorched and jagged. The final, desperate blow of a mech whose spark was guttering.

"I will not falter again," Optimus clarified. "I will bring him down. I will end this."

It was a promise. To himself and to Cybertron and to the Autobots who gathered under his banner.

Sideswipe's helm dipped in understanding, field barely lit at the edges with approval.

"It won't be easy," he murmured, one hand rising to touch the score across his chestplate, flecks of gold interspersed.

Optimus cycled a ventilation, his optics shifting back to the battlefield. "Few things are."

***


	2. Chapter 2

In the wake of fire and agony and spark-searing grief, the broken warrior became a surprising source of solace.

Optimus would seek him out, bitter and exhausted, and Sideswipe would welcome him with open arms and ports, never asking why because he already understood.

Consolation was found in the crackling surges of overload, the comforting warmth of another frame held close to his, the exploration of curious fingers smaller than his own, the searing heat of pleasure that blanked out everything else.

The taste of Sideswipe's spark was as achingly familiar as it was foreign. Optimus drew strength from it and a certain measure of relief. All was not lost. _He_ was not lost. At least, not yet.

That he could offer Sideswipe the same measure of comfort eased the ache in his spark. Because Sideswipe also suffered. What Optimus had considered an act of strength, Sideswipe berated himself for what he called a weakness.

Self-preservation, he claimed. Hurting his twin before the pain could consume him.

Guilt tore ragged holes in what was left of Sideswipe's spark. He didn't recharge so much as shut down all but emergency systems for a short time. He was still a fierce warrior on the battlefield, but in the downtime between one clash and the next, he faltered.

They were both of them broken beyond what a medic could fix. Though Primus knew that Ratchet tried.

"We're going to lose Tyger Pax," Optimus said one grim cycle, slumped as he looked out over Iacon, the last bastion against the Decepticon advance. "And Megatron will claim the Allspark."

His hands clenched on the railing, defeat curdling inside of him like a festering case of cosmic rust. The necessary change in himself had been effected, but it was still not enough. The Decepticons, outnumbering the Autobots nearly two to one, had rampaged across Cybertron and the Autobots were barely able to slow their advance.

The shadows beside him shifted, armor catching a glint of street lighting. "Would that be such a bad thing?"

Optimus' plating rose and fell, clinging tight to his substructure, reflecting the inner turmoil. "I fear what he will do with such unbridled energy. The Allspark, like Cybertron, is a neutral entity."

"And hiding it is of no use."

His helm dipped. "He would tear what remains of Cybertron apart to find it, caring little for who or what might stand in his way."

Hands landed on his hips, sliding around slowly, palms flatting on Optimus' abdominal plating. A frame pressed tight against his backplate, thrumming with a familiar pulse, energy field reaching and coiling with Optimus' own.

"Destroying it isn't an option either," Sideswipe murmured, and it wasn't a question.

Optimus was silent. Neither he nor his cadre of tacticians had an answer. The fact remained, with the Allspark in hand, Megatron would win the war.

Fingers teased over his thoracic ports, a second hand rising to trace the seam of his chestplate. The leisurely exploration and the comfortably familiar touches sought to ease his tension. Optimus wanted to be enveloped in that comfort but his processor would not rest, cycling over and over the problem at large.

"There was an unspoken rule in the Pit," Sideswipe said, and his words were halting, as though pulled from somewhere deeply buried. "If you had something valuable you couldn't protect and couldn't destroy, then you sent it away."

The embrace tightened with a creak of metal on metal, and a long ventilation escaped the warrior's vents. His field rippled, ringed on the edges with age-old grief.

"It was the only way to be sure," Sideswipe added, rebooting his vocalizer to clear the creeping static. "No matter how much it hurt."

Optimus lowered his helm. "That would be the end of Cybertron."

"We're already at the end. With or without the Allspark."

Silence fell, growing between them.

Optimus knew that Sideswipe was right. If he could not defend it, could not destroy it, and could not hide it, what other option did he have but to cast it away?

He turned away from Iacon, shifting in the embrace until he faced Sideswipe, one hand lifting to cup the warrior's helm. "If I asked, would you tell me what it was you sent away?"

Sideswipe's gaze dropped, optics cycling dim. It was an answer without words.

"Do you regret it?"

"Every orn that passes." Sideswipe fingers traced the line of Optimus' backstrut and he lifted his helm. "But I would make the same choice over and over again."

To any other mech, such a statement lacked sense. But Optimus understood it.

"It's late," he said, thumb sweeping over Sideswipe's cheek arch. "Come to berth."

Sideswipe needed no further encouragement. He'd been trying to urge Optimus to recharge and rest all along.

They tumbled into the plush berth, Optimus' only nod to his station. Sideswipe's ports were already open, welcoming, spitting charge and Optimus' cables surged free, clicking home with a snap-crackle of pressing need.

Sideswipe moaned, hands grasping, hooking in thick plates of armor no Prime before Optimus had ever carried. Sideswipe became a frame of motion, rising and falling to the pulse of their connection, need and lust surging in strong bursts through the link.

Pleasure, Optimus reckoned, was simple, easy. He could give and Sideswipe would accept and complications were abandoned in the sweet ebb and flow of charge.

Desire could not be feigned and it rose in Sideswipe's field, blanketing Optimus in unfettered lust. Optimus swallowed the first pleasured cry with a kiss, but his mouth wandered further down, lips tracing Sideswipe's chestplate, following the fine corrugated seams. His glossa nudged the narrowest line down the center, the armor plate humming with warmth beneath his mouth.

Sideswipe shivered from helm to pede, plating rippling, arching up toward Optimus' mouth. Acceptance and permission swirled into one as his chestplate cracked a fraction, pale sparklight seeping through, spilling onto Optimus' face. The heat of it tingled the tactile sensors on his glossa, but his olfactory sensors worked just fine, and he could taste the sheer, undiluted energy, light and heavy all at once, hopelessly addictive.

Optimus cradled the smaller mech with his hands, fingers dipping into broader seams at joints. Their cables grew hot, the scent of heated metal filling the room. Optimus' own chestplates rattled but he didn't dare release them. No matter how much his spark yearned for the touch of another, he couldn't risk it.

Another full-frame shudder struck Sideswipe, whose helm pushed back against the berth, baring the thick cables shielding his intake. He sucked air through his vents, optics dim and unfocused. "Optimus, please."

Need was a molten stream from Sideswipe to Optimus and back again. His circuits hummed with charge and static lit the room, especially inspiring as it reflected off silver armor. Sideswipe's spark flared, fingers gripping tight.

Optimus mouthed the edges of Sideswipe's chestplate, glossa dipping into the narrow split, touching the intangible. He tasted energy and grief and the distinct, sharpness of ozone.

Sideswipe's backstrut arched, frame crackling with electricity, his overload pouring across the link. Pleasure bombarded Optimus, cresting at the first palpable flare of a damaged spark.

Optimus pressed his helm to Sideswipe's chestplate, optics offlining as he shuddered through his own overload. He could feel the warrior thrumming against the platelets of his helm, the heat of Sideswipe's frame a satisfying balm to his inner turmoil.

And still the connection remained hot and hungry between them, one overload never enough to chase away the dark. Sideswipe's eager hands proved his willingness to continue, his systems audibly cycling back up toward blinding ecstasy.

It was several joors yet before Optimus was expected anywhere. He planned to take full advantage of it.

He dragged his mouth up toward Sideswipe's, capturing the warrior's lips for a fierce kiss, moaning as his panels clicked open and Sideswipe's cables sank into his ports immediately thereafter, completing the loop.

This, Optimus decided, was a far more worthwhile venture than recharge.

***


	3. Chapter 3

Privacy was so rare on Diego that it was nonexistent. They recharged in the open, in their alt-modes. Ratchet performed surgery in a warehouse barely big enough to house them in root mode. Optimus himself had to stoop just to fit within it. Attempts to go elsewhere for privacy were met with much twitching from the humans. They didn't outright forbid it, but the hemming and hawing and shuffling of little feet were enough implication.   
  
Nonetheless, privacy became an utmost need the moment Optimus learned the identity of their newest arrivals. He paced back and forth in the limited confines of a storehouse – all that could be had on short notice – and avoided the crates of supplies. He waited with atypical impatience for Ratchet to finish berating one of his favorite patients and release said patient to his superior for a debriefing.   
  
At least, that was the excuse Optimus had given their human allies. He paused, sensors sweeping through the warehouse, and detected no human presence, cameras or otherwise. This time, they'd honored his request.   
  
The warehouse door clattered open and Optimus turned toward, it spark hammering in his chest, his hands tightening at his sides. His plating rattled with indecision; should he be cautious or eager?   
  
Sideswipe stood in the frame before he rolled inside, shoving the door shut behind him. His armor gleamed with fresh welds but his optics were bright and energized. The flickering fluorescent lights didn't do him justice. Certainly, Sunstreaker would have protested, had he still functioned.   
  
Primus.   
  
Optimus wasn't sure who moved first, only knowing that their frames collided with a shriek that must have been audible across base. Optimus' field rose up like a tidal wave, crashing down, enveloping Sideswipe in an instant.   
  
Sideswipe's field replied in kind, rippling out, burrowing into the narrow spaces of Optimus' own, fitting into each niche like a missing puzzle piece.   
  
Relief danced on the tip of Optimus' glossa, but words were not enough. His panels popped open and Sideswipe's cables sank home without hesitation.   
  
There was a moment of brief unfamiliarity. It had been vorns upon vorns since their systems last synched. Optimus had changed, became something altogether different than the unskilled Prime who first fell to Megatron. Sideswipe, too, had become like a stranger, all hard angles where he used to have soft edges, and a bitterness deep down inside.   
  
But beneath all those differences, Sideswipe's bright spark gleamed with familiar trust.   
  
What to call this feeling? This pleasure and relief all rolled into one pulsing wave? There were no words sufficient.   
  
Optimus dropped to his knees, all the better to embrace Sideswipe, his helm pressed to a silver chestplate. He could feel the thrum of Sideswipe's spark beneath the thick armor, the familiar off-rhythm of another twin. His hands pressed against Sideswipe's back, fingers hooking beneath the imbricated plates.   
  
Sideswipe was trembling, too. One hand cupped Optimus' helm, stroking his antenna. The other pressed between Optimus' shoulders, at the apex of his backstrut and just below his helm. It was a particularly vulnerable section of Optimus' frame, armor thinner here by design, and Sideswipe knew it.   
  
Sideswipe's panels popped open and Optimus extended his cables, completing the connection and fulfilling the loop. A melange of images peppered with emotion and sensory data assaulted Optimus' system. He shuddered, pressing harder against Sideswipe, as his partner's loneliness and worry and grief and affection bombard him all at once.   
  
His own data echoed Sideswipe's. Rolled into it was the fresher sorrow, the regret for what had been necessary. His hand had not been the one to deal the final blow and that, too, was a regret.   
  
“I should never have agreed to the transfer,” Optimus said, his voice edged with static and overly loud in the otherwise silence of the warehouse.   
  
A grating laugh resonated in Sideswipe's chassis. “As if Prowl would have given you another choice.”   
  
His tactician had argued, long and loud, that Sideswipe was needed elsewhere. That Optimus did not have space for another member on his team, and Optimus, unable to find an argument that wasn't rooted in selfish desire, had been forced to agree.   
  
“Mmm.” Optimus stroked his fingers down the planes of Sideswipe's back, tracing unfamiliar lines of armor. Sideswipe had upgraded over the vorn. “I had feared you offline.”   
  
“I'm not that easy to kill.”   
  
Pleasure stirred in a lazy current, chasing off the lingering echoes of grief and regret. “A fact for which I am grateful.” Optimus shuttered his optics, soaking in the welcome pulse of Sideswipe's field. “I understand now what you meant, all those vorns ago. But in the end, I was still incapable of doing my duty.”   
  
Sideswipe made a noncommittal noise. “For someone like you, maybe it's better that way.” A wry note colored his vocals. “I'm a warrior. Killing's what I do. But you're a Prime who was supposed to lead in peace.”   
  
“Weren't you the one who told me I'd have to leave that behind if I hoped to find victory?”  
  
“What? I can't be wrong?”   
  
The last of the apprehension left Optimus in a heavy ventilation. Yes, Sideswipe had changed, but he was also the same mech that first inspired Optimus, then helped fill the void left in his spark.   
  
“The war is over,” Optimus said and it never ceased to ease the band around his spark every time he acknowledged that aloud. “You are welcome to be whatever you wish.”   
  
One finger stroked down his audial before cupping his jaw, tilting his helm upward. Optimus obliged, onlining his optics, greeting a Sideswipe who looked the most serious Optimus had ever seen him.   
  
“And what if I want to stay with you?” he asked.   
  
“I would not protest,” Optimus replied with no hesitation on his part. And this time, there would be no one to argue, not that Optimus would allow it. Perhaps, just this once, he could be selfish.   
  
Sideswipe grinned, finger teasing at the cables on his neck with little zaps of charge. “How long would you say we'd have before we're bothered?”   
  
Optimus' engine rumbled. “Long enough.”   
  
And if a human got an eyeful, it was his own fault.   
  


***


	4. Indivisible 4.0

**Summary for the Chapter:**

> Timeline: during and post-RotF  
> Characters: OptimusxSideswipe, Ironhide, Lennox, Ratchet  
> Description: Optimus had not made any promises. Sideswipe wished he had demanded one.

And then Optimus died and Sideswipe could only stare in horror as his future collapsed, chassis smoking and optics dark.  
  
Late. He was too late.  
  
Ironhide was yelling and Bee was gone, taking the twins with him.  
  
Ratchet couldn't fix him. He scanned and he tried and he shouted for Ironhide to help him, but there was nothing a miracle-worker could do to fix death. He'd already tried that with Jazz and look where it had gotten them.  
  
Sideswipe had to hold himself together because no one was supposed to know. Especially not Jolt who was looking at him like he should have answers and Arcee who just wanted a target and permission.  
  
Sideswipe didn't think he could hate any sentient creature more than Jhiaxus until the humans dropped Optimus like trash. He waited, weapons primed to fire, for Ironhide to give the okay. He almost fired anyway when Ironhide told them all to stand down because it wasn't right, what their so-called allies had done, and it wasn't fair either.  
  
He'd never wanted to kill an organic so much.  
  
This wasn't how his world was supposed to end.  
  
Ironhide and Ratchet argued over what they were supposed to do next. Ratchet wanted to leave; Sideswipe agreed with him. Ironhide wanted to stay because that was what Optimus would have wanted, and a part of Sideswipe wanted to agree with that, too.  
  
Bee was still missing along with the twins.  
  
Arcee was fighting with herself.  
  
Jolt pretended to be in recharge.  
  
Optimus still lay on the tarmac where they'd discarded him.  
  
Sideswipe circled him, hands clenching in and out of fists. His optics blazed, and his field was rattled and uneasy.  
  
The emptiness threatened to consume him all over again. He wanted to claw at his chassis, go through his chestplate, and tear out his spark chamber. Nothing less could ease his pain.  
  
His ventilations hitched.  
  
Optimus had not made any promises. Sideswipe wished he had demanded one.  
  
A keen rose in his vocalizer and Sideswipe locked it down.  
  
No one could know. Not even now, with Optimus gone, could anyone know.  
  
He circled slower, swords rattling, threatening to emerge. If anyone asked, he was guarding Optimus.  
  
This was the humans' fault.  
  
Frag Optimus for wanting to protect them.  
  
Frag Sideswipe for being too late.  
  
Frag Megatron and Starscream and Grindor.  
  
Three to one and Megatron put a fusion blast through Optimus' spark without hesitation. None. Even Sideswipe had hesitated when it came time to taking down his twin. And Optimus hadn't been able to land the final blow back in Tranquility.  
  
Not Megatron.  
  
Sideswipe screeched to a halt, his plating rippling before it clamped down tight. He tilted his helm back, toward the sky, offlining his optics.  
  
He had already killed one twin. Megatron would pay for taking the other.  
  


o0o0o

  
  
He stayed. He guarded Optimus all night.  
  
Lennox came out once, offering to spell him for a bit, but Sideswipe shook his helm. Not interested.  
  
He offered a covering for Optimus, to protect him from the elements, but all they had was a tarp and that didn't strike Sideswipe as right either.  
  
Ironhide came by, tried to convince him to recharge, but Sideswipe didn't need any. He felt fine.  
  
“You aren't foolin' no one, kid,” Ironhide said with a hot ventilation. “But I'll leave ya alone for now.”  
  
Ratchet came next, of course he would. He scanned Sideswipe, quick and perfunctory, grunting an acknowledgment and then he knelt by Optimus. He laid a hand on their leader's shoulder as though convincing himself Optimus was well and truly offline.  
  
“What're we going to do?” Sideswipe asked, because Ironhide would spew battle tactics and aggression at him, but Ratchet would say it like it is.  
  
“We fight,” Ratchet said, helm bowed. “We fight because we can't leave, and I'll be fragged if we let Megatron win.”  
  
“The humans won't let us.”  
  
Ratchet lifted his helm, optics burning a white-hot fire. “They can't stop us.”  
  
That was what Sideswipe wanted to hear. His systems hummed with charge, fingers sliding in and out of fists. His spark ached to cause damage.  
  
And then his comm unit beeped.  
  
Sideswipe tilted his helm, noticing that Ratchet did as well, both of them receiving the same message. It was vague, stilted, but it contained several vital clues.  
  
Egypt. The boy.  
  
Hope.  
  


o0o0o

  
  
Optimus found Sideswipe on the tarmac in the middle of the night. He sat on the ground, his knees drawn to his chestplate, his arms braced across them. His helm was bowed, his optics offline. Moonlight glinted off his armor, still pitted and scored from the battle. How he'd eluded Ratchet's attention, Optimus did not know.  
  
A human would mistake Sideswipe's stillness for recharge.  
  
Only a Cybertronian would be able to detect the maelstrom of conflict in Sideswipe's energy field. With his spark in such disarray, Optimus wasn't sure how Sideswipe could stand to remain so still.  
  
He stood behind Sideswipe, casting a long shadow, struggling to find the right words.  
  
No one could know. Here, out in the open, they had no privacy. But most of the base was packing up, licking their wounds, and maybe this once--  
  
“I've been sitting here, asking myself the same question over and over,” Sideswipe said before Optimus could form the words. “And I realized it's never going to end.”  
  
Optimus tilted his helm. “What do you mean?”  
  
Sideswipe made a vague gesture to the distance. “The Allspark is gone. Megatron was dead; now, he's not. And you...” He trailed off, fingers closing into a fist as he drew his hand back. “This war is never going to end. No matter who lands the final blow, neither of us can win.”  
  
Optimus lowered himself to one knee, wincing as the matrix shifted within him, moving his internals around to make room. It repeatedly nudged against his spark chamber, causing flashes of static and discomfort with each twitch. “I apologize.”  
  
“For what?” Sideswipe huffed a ventilation. “Failing to keep a promise you never made?”  
  
Optimus flinched again, relieved that his partner couldn't see it. He reached for the mech, to lay a chaste arm on his shoulder, surely an action that couldn't be misconstrued by prying optics or eyes. “Sideswipe--”  
  
A burst of motion, Sideswipe moving so fast that it had to hurt, avoiding Optimus' hand and lurching to his pedes. It put them optic to optic at least, especially when Sideswipe whirled around, just out of arms reach. His optics were bright, but guarded, his field withdrawn entirely.  
  
“I watched you die,” Sideswipe said, static crackling on the last syllables. “And I kept my silence. Don't test my restraint.”  
  
“It was not a test. It was an offer.” Optimus waited, patient, for Sideswipe to bridge the gap.  
  
The matrix squirmed, restless, as though trying to soothe his aching spark. Optimus knew, viscerally, that Megatron was alive, but Optimus could not and would not go back down that route. No matter what the ancient relic in his chassis demanded.  
  
Sideswipe stared at him. “Have you lost your processor?” His optics skittered to the left and right as though searching for an answer, his frame rocking back and forth on his pedes.  
  
Optimus pushed himself to his pedes and reached for Sideswipe again, relief flooding through him when the frontliner didn't evade him this time. He lay his hands on Sideswipe's shoulders, thumbs brushing inward, over Sideswipe's chestplate. He could feel the thrum of the frontliner's spark, an off-rhythm hum that echoed Optimus' own.  
  
“Death,” Optimus said, “puts certain matters into perspective.”  
  
Sideswipe's plating rattled beneath his hands. “We can't.”  
  
“Right now? Of course not.” It would be selfish and foolish to make such commitments with Megatron yet out there. “But after the end, there will be nothing to stop us.”  
  
“Megatron--”  
  
“--has died once,” Optimus interrupted, his vocals harsh and flat, unable to hide the fury he felt with his brother. “I will not fail a second time.”  
  
The Matrix lurched within him, angry and argumentative, but Optimus pushed it down. He would no longer be led by the shackles of same ancient artifact. Such was what caused the war in the first place, and he was through living by the commands of a relic.  
  
He would be Prime, but it would be on his own terms from now on. Because following the rules had helped no one, least of all himself and his Autobots.  
  
Shock buzzed in Sideswipe's energy field before he drew it back under his control. He dipped his helm, cycling a ventilation.  
  
“We aren't supposed to make promises,” he said, but there was an echo of want in his tone, a repressed desire now daring to hope.  
  
“I am changing the rules,” Optimus said, and he ran his finger down Sideswipe's chestplate, making his intentions clear.  
  
A shiver rippled through Sideswipe, his field radiating outward, open and inviting. “Yeah, okay,” he agreed. “After.”  
  
Warmth flushed through Optimus and finally, the Matrix went still. Whether because it was satisfied, or wanted to save the effort of protest for another day, Optimus did not know. Nor did it matter.  
  
“After,” he said, and this time, it was a promise.  
  
One he intended to keep.  
  


***


	5. Indivisible 5.0

**Summary for the Chapter:**

> Sideswipe did what he had to do because there was no alternative. So, too, would Optimus.

**Notes for the Chapter:**

> This one actually takes a step back in the Indivisible timeline mostly because I started writing it as a post-DotM fic but Sideswipe insisted he wanted to share a little backstory first. So there ya go.

Recharge remained the hardest part.   
  
The humans thought the Cybertronians shut down, like a computer, but that was far from the truth. The processor continued to function in recharge, much like the human brain, running autonomic processes and maintaining a certain degree of conscious.  
  
Sideswipe was always painfully aware of being alone. It was a constant on the edge of his conscious. Thousands of years couldn't erase what had become second nature to him. He had memorized Sunstreaker's frame and spark as well as he knew his own and the middle of recharge was when his spark cried the loudest.   
  
Automatic pings to a spark long extinguished. Flashes of panic when his system realized Sunstreaker was gone all over again. Guilt would swamp him next and his spark would ask why and his processor would reply in kind, pinging his memory core and--  
  
Every time he recharged, Sideswipe relived the moment he tore out Sunstreaker's spark.   
  
He saw, all over again, Sunstreaker snarl. The dim of betrayal in his twin's optics, the Decepticon badge bright and seared on Sunstreaker's chestplate. Energon was thick and gummy on Sideswipe's hands, his own wounds numb, his spark in agony.   
  
He told himself, over and over again, that what he'd done was necessary.   
  
Over and over again, he failed to believe it.   
  
Recharging with others made it easier to bear for a time so yes, Sideswipe berthhopped. It was better than the alternative if only by a fraction.   
  
And then by accident or Primal design, Sideswipe wound up in Optimus' berth and it was the closest he came to peace. Optimus' spark felt the same and Sideswipe luxuriated in that. Better that Optimus needed him, too.   
  
He needed no other berth. Except that Optimus being Prime couldn't always share his. After the comfort that was so close to perfect, no other berth would do.   
  
Sideswipe endured because he had become good at it. Waiting for Prime was a torture into itself, but the moments when he could and did share Optimus' berth were bright spots of light in the darkness of the war. The knowledge that he could help Optimus when the Prime disdained the confidence of all others soothed Sideswipe on some level.   
  
They pretended to understand, the surviving senators and council, the multitudes of medics and army officers, the priests, but none of them could. They didn't know what it was like to watch your -- lover/brother/ _spark_ \-- turn on you. They couldn't feel each blow like a physical wound, or endure the internal debate that called you a traitor.   
  
Sideswipe did what he had to do because there was no alternative. So, too, would Optimus.   
  
Over time, that understanding grew into something more. Grew into something without audible promises, but understood intent.   
  
Sideswipe would never feel whole again, but with Optimus, he could at least feel happy. Content even.   
  
It was an arrangement that suited Sideswipe. Optimus understood like no one else.   
  
He would open his arms without question or hesitation, extend his field, and embrace Sideswipe with eager enthusiasm. More than that, Optimus would willingly surrender. He would lay back, unmasked and vulnerable, ports spiraling open and crackling with discharge. His optics would brighten, field filled with unmistakable need and that was so easy to fulfill.   
  
Optimus was Prime, would always be Prime in Sideswipe's optics. But Sideswipe wasn't forged a warrior. He became one out of necessity. He served Prime by choice, unlike many other Autobots.   
  
So when he crawled into that large berth and those open arms, he kissed Optimus, not Prime. He memorized every inch of Optimus' plating with his hands. He sank each cable with need and not reverence because Prime did not exist here, only Optimus.   
  
Prime was simply Optimus, grief-stricken and in need. He was a mech Sideswipe could easily love and that was what mattered, even if the end result couldn't be one of his choosing.   
  
Optimus made the darkness fade and Sideswipe prayed he could be the same in return. One broken spark to another.   
  


***


	6. Indivisible 6.0

**Summary for the Chapter:**

> The end of the war, and the start of something new.

Sideswipe dragged himself back in time to see the aftermath, the scattered remains of Sentinel Prime and Optimus standing triumphant over Megatron, holding an axe to his twin's helm.   
  
Sideswipe's spark lurched and he grasped a building to keep himself upright, one leg threatening to buckle beneath him. Even from this distance, he could read Optimus' field. He could feel the indecision, and it wasn't hard to pick out the words.   
  
Megatron pleading, difficult to tell whether his offer was sincere or another deception.   
  
Optimus hesitating, staring his brother in the optics and maybe daring to believe.   
  
Sideswipe knew this moment. He had been there before, only Sunstreaker had been defiant, all but daring Sideswipe to strike. He'd believed, until the last second, that Sideswipe wouldn't do it. And maybe buried in that, was a smidgeon of rivalry that threw Sideswipe over the edge.   
  
Optimus would always be a better mech than him. Which was only proven when the axe lowered and Optimus' optics cycled down.   
  
“Leave,” he said, vocals low but not such that Sideswipe couldn't hear them. “And know that you have lost.”   
  
Sideswipe's leg surrendered and he dropped, the warning cries at the back of his processor louder than he could ignore.   
  
Over, his spark shouted at him, it's over.   
  
And then the darkness claimed him.   
  


o0o0o

  
  
Sideswipe woke to the sounds of celebration, though he couldn't understand why. Ironhide was dead and too many before him. His HUD was giving him status updates, listing others like Dino and too many humans to name.   
  
The war had been won, but at what cost? Optimus had agreed to a truce, though no one save Sideswipe would understand why. What did that mean for the rest of them?   
  
What did that mean for Sideswipe?   
  
He onlined his optics, staring dully at the warehouse ceiling, wondering if it was worth the effort to move.   
  
“Don't. I haven't finished recalibrating that leg yet.”   
  
Ratchet's voice, a warning, and Sideswipe stopped thinking about moving. He turned his helm, getting a better look at the mech beside him, whose expression did not reflect the joy Sideswipe could hear somewhere beyond the building.   
  
“Will I ever walk again, Doc?” Sideswipe asked, in a flat tone that was an echo of his usual humor.   
  
Ratchet rolled his optics. “Yes, though if I had my say and for the sake of my sanity, I'd keep you berthbound. Somewhere not here.”   
  
Sideswipe forced a dry chuckle. “Some things don't change, I guess.”   
  
“And some things do.” Ratchet paused and looked up from his scanner, tilting his helm. “What's the last thing you remember?”   
  
He didn't wince by sheer force of effort. “Chicago. The battle.” He paused, remembering the look in Optimus' optics, the relief in the slow way he lowered his weapon. “A truce.”   
  
“You could sound a little more excited,” Ratchet said as he turned away, only to return with a cube of energon. “The war's over. Here. Sit up.”   
  
Sideswipe pulled himself upright, grunting as the action pulled on a few fresh welds, and reached for the energon. “It's been over before.”   
  
“Mmm. Good point.” Ratchet stepped back, giving Sideswipe a critical look. “You do know that Megatron left.”   
  
Sideswipe almost choked on his energon. “What?”   
  
Ratchet's field hit him with an almost smug certainty. “He and the surviving Decepticons returned to Cybertron. To rebuild. We will stay on Earth until they – as in Megatron and Optimus – are certain we can integrate without issues.”   
  
“Integrate?”   
  
“Live together again. Peaceably.”   
  
“I know what it means,” Sideswipe snapped, and then hated himself for doing so. He ducked his helm sheepishly. “Sorry.”   
  
Ratchet inclined his helm. “You should talk to Optimus,” he said, which seemed an incongruent thing for him to say. “It might help.”   
  
Sideswipe drained his cube, tossing the empty container to the side. “What is that supposed to mean?”   
  
“You've never been very subtle. And Optimus doesn't know the meaning of the word,” Ratchet replied and turned away, humor edging into his field. “Take it easy on that leg. If you frag it up again, you can suffer for awhile.”   
  
Sideswipe gaped at the medic. “But--”  
  
“He had a meeting with Mearing and the President but it should be done already. He's probably by the river,” Ratchet added, busying himself with some menial task, his back to Sideswipe. It was the closest thing Ratchet had to a dismissal.   
  
Sideswipe slid off the berth, tested his knee, and found that it rotated smoothly. He would have no issues with it. Though he would listen to Ratchet and not engage in anything overly acrobatic.   
  
He paused, however. “You're not celebrating?”   
  
“No,” Ratchet said.   
  
Sideswipe waited for him to elaborate, but Ratchet didn't. And well, Sideswipe could understand why. So he left it at that. Sometimes, a victory could feel hollow and maybe that was the case for Ratchet.   
  
Sideswipe rolled out of the makeshift medbay, wincing at the onslaught of noise that attacked his audials. It was dark, but the sky was lit up with fireworks, and there was music and cheering and chatter. Helicopters wove in and out of the broken buildings in Chicago, a grim search for survivors even amid the celebration.   
  
Sideswipe cycled a ventilation and scanned for Optimus, his sensors picking up the Prime near the river, as Ratchet had said.   
  
Optimus stood like a silent guardian, staring out over Chicago, his hands clasped behind his backplate. He didn't turn when Sideswipe approached him, though he had to have known Sideswipe was coming. Optimus' battle programming and sensors were too acute to miss an oncoming frontliner.   
  
“So,” Sideswipe said, coming to a stop beside Optimus, staring at the ruins of one of the human's great cities. “A truce.”   
  
“Yes.” An undefinable emotion rippled through Optimus' field as it reached out, gesturing for Sideswipe's own. “Killing him would have solved nothing.”   
  
“Optimus, you know you don't have to explain yourself to me.”   
  
“No, I do not.” Optimus shifted, unclasping his hands, and the full weight of his gaze fell on Sideswipe. “Because you, of all my Autobots, will understand.”   
  
Something squirmed, restless and unkind, through Sideswipe's internals. The urge to shout and stake a claim, made his plating clamp down.   
  
“Yeah,” he said and hated himself for the selfish thoughts that tried to override his spark. “Congratulations, by the way. It's finally over.” He thought he should walk away while he still had some dignity.   
  
“One could also consider it a new beginning.”   
  
Sideswipe managed a smile, lopsided at best. “That, too.” He drew in a ragged ventilation. “Starting over. Second chances. All that altruistic slag. That's what it's about, right?”   
  
It hurt. It wasn't supposed to, but it did.   
  
Optimus' battle mask slid aside and he frowned. “Sideswipe, Megatron is gone.”   
  
“Yeah, that's what Ratchet said.” Sideswipe rolled his shoulders, wondering if he could make a graceful exit. “Eventually, we'll get to go back, too. And everything will be as it should be.”   
  
Except Sunstreaker would still be dead and Sideswipe would always carry the knowledge that he was the one to land the final blow. Was he bitter that Optimus was able to keep his twin when Sideswipe hadn't? Maybe.   
  
He fought back a sigh. “Optimus--”  
  
There were no mistaking the arms that wrapped around him, or the field that washed over him from helm to pedes, warm and familiar. He hadn't seen Optimus move, nor read the intention in his optics, but the embrace had enclosed him all the same.   
  
“Megatron will continue to be Lord High Protector, that is a term of the truce,” Optimus said, his vocals rumbling over Sideswipe. “But he will never again share my berth. That privilege has been reserved for another.”   
  
Sideswipe's intakes hitched. He brought up his arms, wrapping them around Optimus, daring to believe that Optimus was offering what Sideswipe thought he was offering.   
  
“And in case I was not clear, that mech is you,” Optimus added, fuzzy warmth in his energy field. “Provided you want to accept the invitation.”   
  
“Mechs will talk,” Sideswipe said. He wasn't protesting, however, simply making an observation.   
  
Amusement rumbled through Optimus' vocalizer. “Since when has a little gossip bothered you?”   
  
“Since never. I was worried about you.” Sideswipe couldn't stop the grin that formed on his lipplates, though Optimus couldn't see it. “You do realize we're in plain sight, right?”  
  
“I am aware.”   
  
“Just making sure.”   
  
The war was over, Sideswipe said to himself.   
  
Maybe now he could believe it.  
  


***


	7. Indivisible 7.0

**Summary for the Chapter:**

> In the end, it's the difference between choice and chance.

Cybertron was not the home Sideswipe remembered.   
  
The war had been over for centuries. On Earth, the years had swept by, the humans ever-changing, the Cybertronians a constant observer.   
  
Megatron and his Decepticons had worked hard. They had rebuilt. They had governed themselves. They had changed.   
  
Megatron most of all.   
  
“Welcome,” he said as Optimus and his hand-picked team of Autobots stepped off the rebuilt Ark. “All of you, welcome.”   
  
Gone were the familiar trappings of the Decepticon warlord: the sharpened denta, the talons, the spiky armor. Gone were the Decepticon brands, replaced by the glyphs of his former station, that of the Lord High Protector. If Megatron was trying to make a statement, he succeeded.   
  
Sideswipe, suddenly, was all too aware of the daggers strapped to his forearms. They somehow felt a betrayal to the peace, though he had made it a vow to never let Optimus go anywhere without protection. The Decepticons weren't the only threat and Cybertronians had made nothing but enemies across the universe.   
  
But this was the first visit, the first face-to-face meeting since Optimus granted Megatron mercy and banished him to Cybertron. The truce had held but anything could ruin it. Peace remained tenuous, old grudges proving the same.   
  
Optimus was here, with Ratchet and Sideswipe, to determine if integration was possible. If Megatron had rebuilt enough infrastructure that the two factions could live together as one people again.   
  
“Thank you,” Optimus said, tones gracious and polite.   
  
“How was your flight?” Megatron asked, the perfect host, as Optimus fell into step beside him. They were immediately flanked by Thundercracker and Skyquake, Megatron's new lieutenants in Soundwave, Starscream, and Shockwave's absence.   
  
“Uneventful.”   
  
Sideswipe fell in line behind them, Ratchet next to him. He watched Megatron, failing to conceal his glare at the shiny, imposing frame of the reformed Lord High Protector. One who looked as though he belonged whilst walking next to the greatest of the Primes.   
  
Sideswipe resisted the urge to touch his chestplate, where Optimus had waged a claim and sealed his promise.   
  
The bond between brothers, Sideswipe knew, could be a hard pull to resist.   
  
He ignored the way Ratchet watched him, optics full of awareness. He and Optimus had not been subtle, but even less as the years wore on and more Autobots and refugees arrived on Earth. Ratchet, busybody that he was, seemed to think he needed to watch over them from however far.   
  
Megatron continued to speak, tones filled with pride as he relayed the scope of the Decepticon effort: the rebuilding, the newly opened mines, the return of Cybertronian citizens, many of whom had claimed neutrality.   
  
It was impressive, Sideswipe forced himself to admit, ignoring the seething waves of jealousy.   
  
Megatron had focused his efforts here, in Iacon, the former Autobot stronghold rather than beelining for Kaon as Sideswipe would have anticipated. They had landed on a true airfield, rather than a makeshift one, and were surrounded by buildings. Megatron directed their attention to an actual medcenter – promising Ratchet a tour later. There's also an energon refinement and dispensary, several residential buildings, an office building, and more stable roads than Sideswipe could count.   
  
Sideswipe wished Megatron could have been a little less productive, if only to make him less appealing. But no. Megatron had taken the truce seriously, working hard to make amends for his many, many mistakes.   
  
Sideswipe hated him just a little more.   
  
Ahead, Megatron and Optimus continued to walk side by side, in step, like the ruling diad they had been once upon a time. Their frames complemented, a matched set now that Optimus had discarded the flamboyant flames of Earth's alt-mode. They looked as though they belonged together.   
  
Sideswipe twitched. He was silver. That was where the similarity ended. He was smaller than Optimus, less powerful, with less processing power.   
  
Not a mech often struck with insecurity, Sideswipe found himself floundering. After all, when had he ever found reason to compare himself with Megatron?   
  
When it boiled down to it, Sideswipe was not Optimus' twin.   
  
This was a bad idea. He should not have come. Should have sent Prowl in his place, like the tactician had argued. Or let someone more tactful come, like Smokescreen. Or someone friendlier, like Hound. Anyone really, so Sideswipe didn't have to trail along behind Megatron and Optimus, feeling as out of place as a human might be.   
  
The tour continued. Sideswipe feigned interest, realizing with every passing building that in all likelihood, the Autobots would be joining the Decepticons on Cybertron sooner rather than later. He tried to ignore the unsteady sensation in his tanks, and purposefully avoided Ratchet's optics.   
  
He should not have come.   
  


o0o0o

  
He had never seen anything like this view.   
  
Then again, Sideswipe had nothing to compare it to since he had never seen Iacon from these heights, not before or during the war. It was odd to see the reconstruction so near, but in the distance, the ravages of war still streaked across Cybertron like a weld-scar.   
  
Sideswipe leaned on the railing, watching Cybertron's new sun set in the distance, and marveled at the idea of “night” on this planet. He couldn't remember a time that Cybertron orbited a sun. How lucky that the failed space bridge attempt had dropped Cybertron back out into the gravity pull of a massive star.   
  
Lucky, or perhaps Primus' hand, forgiving his children for their war.   
  
“You do not seem impressed.”   
  
Sideswipe stiffened at the voice, familiar but not wholly welcome. “It's not the view,” he replied and slowly turned to face Megatron. “You've done more than any of us expected.”   
  
The Lord High Protector smirked, a pale attempt at a smile. “How tactful. Though if you expect to stand by my brother's side, you'll have to better hone your political insights.”   
  
Sideswipe frowned and thought of the daggers he left sitting on a chair in his room. “I don't know what you're talking about.”   
  
“Denial?” Megatron arched an orbital ridge and crossed the balcony, approaching the rail. “You are better at the game than I thought.”   
  
Sideswipe cycled a ventilation, forcing himself to be calm. “Is there something I can do for you, Lord Megatron?”   
  
There was no answer immediately. Megatron appeared contemplative as he looked out at Iacon and the work he'd done. Only then did he speak.   
  
“I do have one minor request,” Megatron began and Sideswipe knew it was one he didn't want to hear. “Return my brother to me.”   
  
“I... the slag?” All of decorum departed from Sideswipe's repertoire. “I can't just--”  
  
The Lord High Protector turned, every inch of him bristling menace for all that he was unarmed. “Release him from whatever vow you've earned.”  
  
Sideswipe stiffened, filled with genuine rage, one that was perhaps unwise considering that Megatron could rend him in two, unarmed or not. “That's not my decision to make and even if it was, my answer would still be no!” he growled.   
  
“You think you have the right to claim him?” Megatron demanded, tones laced with affront.  
  
Funny how Sideswipe wasn't intimidated. Well, maybe a little. This was Megatron after all.   
  
“I have the right to stay beside him as long as he wants me,” Sideswipe argued.   
  
Megatron stared at him. “You think highly of yourself, don't you? Even with that shattered bond.”   
  
It took every effort to restrain his temper. Sideswipe's hands clenched into fists. “Sunstreaker's betrayal was his own choice. As was yours.”   
  
Megatron took a step closer, looming without trying, easy when he was two helms larger than Sideswipe. “And you made him regret that choice. Thoroughly.”   
  
Pain, like a lance, straight through his spark. As though time had made that particular decision any easier to bear, or that agony any softer.   
  
“I did what I had to do,” Sideswipe said, feeling again the gaping maw within him where Sunstreaker once was and Optimus couldn't be. “Don't think for a single moment that I don't regret it every moment of my life.”   
  
He once thought that he'd taken the easy way out by taking Sunstreaker's spark when the time came, but now, Sideswipe knew how much harder it was to live with that guilt. To question, every moment of every day, if he had made the right choice. He could have waited, held mercy like Optimus, and Sunstreaker could be standing in front of him right now, declaring he had changed, seen the error of his ways.   
  
This was why Optimus would always be the better mech.   
  
Sideswipe cycled a ventilation and met Megatron's gaze with all the confidence he could muster. “I don't know if you sought me out for a fight or because you wanted something. Either way, I'm not playing your game. I didn't come here for you. I came because Optimus wants me here and that's what matters to me. If you've got a problem with that, take it up with him.”   
  
He didn't wait for Megatron to say anything further. He had no interest in whatever claim or demand Megatron would make.   
  
He'd had his chance. He could have stopped the whole war before it ever began. He could have seen the value in what he'd lost before he ever cast it aside.   
  
If Megatron wanted sympathy, he was looking to the wrong mech for it.   
  
Sideswipe left Megatron on the balcony, even though by rights he should have tossed Megatron off it. This was his room, his balcony, but rather than try to evict the Lord High Protector, he would make himself scarce.   
  
Except that his room wasn't empty.   
  
“Optimus,” he said, surprised and elated all at once. He couldn't stop the happy skip that struck his spark, helping quell some of the lingering hurt of Megatron's words. “I thought you were touring with Ratchet.”   
  
“We finished early.” Optimus glanced past him, optics cycling down in thought, no doubt fully aware of Megatron's presence. “Is everything all right?”   
  
“Nothing is wrong,” Sideswipe answered because he couldn't lie. “Megatron was just leaving.”   
  
A dark chuckle emerged from the balcony behind them, Megatron making himself known. “Calm yourself, brother. I was merely having a chat with your subordinate. It is only my right to speak with the mech serving as my replacement.”   
  
Defeated but not chastened, Sideswipe thought. That described Megatron fully. He could play the part of the foiled warlord to Cybertron at large, but here in the privacy of this room, with only Sideswipe to bear witness to the behavior of the brothers, he could show his true colors.   
  
“Sideswipe is no replacement,” Optimus said, his vocals harsh, a far cry from the neutral, polite tone he'd used at their arrival. His hand rested on Sideswipe's shoulder, a warm and welcome weight. “He is the mech I _chose_ as opposed to the one fate forced upon me.”   
  
No one was more surprised than Sideswipe when Optimus made that bold claim. His optics spiraled wide, mouth opening but no words emerging. Megatron, for his part, startled, visibly jerking back.   
  
“He can't rule at your side!” Megatron all but growled. It was a near thing, his field filling the room with outrage and yes, hurt.   
  
Good, Sideswipe thought. For all that Optimus suffered over the course of the war, it was time Megatron understood how much pain he had caused. How he could not have felt it for himself, Sideswipe would not know.   
  
“Nor shall he.” Optimus stepped up closer to Sideswipe, their armor brushing, a show of solidarity. “You are the Lord High Protector, Megatron, and that is all you will ever be. Any further bond between us is gone and you have only yourself to blame.”   
  
His words were strong, but Sideswipe felt the tightening in Optimus' grip, the shiver in his field indicative of pain. He turned Megatron aside with far more reluctance than Megatron had shown all those millennia ago.   
  
Sideswipe wondered if he would have the same courage, today, to tell Sunstreaker that their bond made no difference. That he would always love Sunstreaker but couldn't bear to have his twin in his berth or beside him.   
  
He wasn't that strong.   
  
“Brother--”  
  
“Do not call me that,” Optimus said, tones harsh and chastising. “You have lost that right. Just as you have no business here, in this room.”   
  
Megatron's mouth opened and shut, his helm dipping down. Tension slicked his frame, and for a moment, Sideswipe feared he would attack. That their truce really had meant nothing and Megatron had only been biding his time.   
  
But then, Megatron audibly cycled a ventilation. “Very well,” he said, defeated. “I will leave you in peace.”   
  
Megatron said nothing further as he left the room, nor did he cast a final glance over his shoulder. He took with him all the tension, leaving Sideswipe to slump a little in relief.   
  
“Has he even apologized?” Sideswipe asked, unable to imagine for himself the sight of someone like Megatron apologizing.   
  
“Once,” Optimus replied. “But it was not enough and disingenuous at best.”   
  
Sideswipe leaned back, feeling the vibrations of Optimus' plating against his own armor, and enjoying the warmth of Optimus' embrace. “I would understand,” he said, though it hurt to do so. “I could learn to share.”   
  
“You could. But I do not intend to do so.” Optimus' hand slid down over Sideswipe's chestplate, palming the seam that would part to reveal his spark and the promise Optimus had made. “And if I have not made myself clear already, perhaps I need to remind you.”   
  
Sideswipe grinned, spark already pulsing in anticipation. “Couldn't hurt,” he said as one of Optimus' fingers traced the length of the seam in a slow, promising slide.   
  
Megatron's loss was Sideswipe's gain and he could finally be confident in that.   
  
Optimus was his and vice versa and while Optimus could not replace Sunstreaker, he was the one Sideswipe _chose_.   
  
In the end, that was what mattered the most.   
  


***

**Works inspired by this one:**

  * [Insoluble](https://archiveofourown.org/works/2750813) by [dracoqueen22](https://archiveofourown.org/users/dracoqueen22/pseuds/dracoqueen22)




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